From 38040755377216ad8983fb4f599fa46e21b8ac50 Mon Sep 17 00:00:00 2001
From: jess <jess@else-if.org>
Date: Tue, 31 Mar 2026 13:00:07 -0700
Subject: [PATCH] fix uniform buffer mismatch between cord-render and
 cord-shader WGSL

---
 crates/cord-render/Cargo.toml          |  2 --
 crates/cord-render/src/lib.rs          |  5 ++--
 crates/cord-render/src/pipeline.rs     | 37 +++++++++++++++++---------
 crates/cord-shader/src/codegen_trig.rs |  4 ++-
 4 files changed, 30 insertions(+), 18 deletions(-)

diff --git a/crates/cord-render/Cargo.toml b/crates/cord-render/Cargo.toml
index 3c1974e..72ef9ec 100644
--- a/crates/cord-render/Cargo.toml
+++ b/crates/cord-render/Cargo.toml
@@ -9,10 +9,8 @@ keywords = ["wgpu", "raymarching", "sdf", "renderer", "3d"]
 categories = ["graphics", "rendering"]
 
 [dependencies]
-cord-shader = { path = "../cord-shader" }
 wgpu = "24"
 winit = "0.30"
 pollster = "0.4"
 bytemuck = { version = "1", features = ["derive"] }
-glam = "0.29"
 anyhow = "1"
diff --git a/crates/cord-render/src/lib.rs b/crates/cord-render/src/lib.rs
index a33744e..07df06d 100644
--- a/crates/cord-render/src/lib.rs
+++ b/crates/cord-render/src/lib.rs
@@ -217,8 +217,9 @@ async fn init_render_state(
     };
     surface.configure(&device, &config);
 
-    let pipeline = RenderPipeline::new(&device, format, wgsl_source)?;
-    let camera = Camera::new(bounding_radius as f32);
+    let scene_scale = (bounding_radius as f32).max(0.1);
+    let pipeline = RenderPipeline::new(&device, format, wgsl_source, scene_scale)?;
+    let camera = Camera::new(scene_scale);
 
     Ok(RenderState {
         window,
diff --git a/crates/cord-render/src/pipeline.rs b/crates/cord-render/src/pipeline.rs
index 3f38790..60643e0 100644
--- a/crates/cord-render/src/pipeline.rs
+++ b/crates/cord-render/src/pipeline.rs
@@ -2,26 +2,33 @@ use crate::camera::Camera;
 use anyhow::Result;
 use bytemuck::{Pod, Zeroable};
 
+/// Matches the WGSL `Uniforms` struct byte-for-byte.
+///
+/// WGSL alignment: vec3<f32> aligns to 16 bytes, vec2 to 8, vec4 to 16.
+/// Total: 80 bytes (multiple of 16).
 #[repr(C)]
 #[derive(Debug, Copy, Clone, Pod, Zeroable)]
 struct Uniforms {
-    resolution: [f32; 2],
-    time: f32,
-    _pad0: f32,
-    camera_pos: [f32; 3],
-    _pad1: f32,
-    camera_target: [f32; 3],
-    fov: f32,
+    resolution: [f32; 2],        // offset  0
+    viewport_offset: [f32; 2],   // offset  8
+    camera_pos: [f32; 3],        // offset 16 (vec3 align 16)
+    time: f32,                   // offset 28
+    camera_target: [f32; 3],     // offset 32 (vec3 align 16)
+    fov: f32,                    // offset 44
+    render_flags: [f32; 4],      // offset 48 (vec4 align 16)
+    scene_scale: f32,            // offset 64
+    _pad: [f32; 3],              // offset 68
 }
 
 pub struct RenderPipeline {
     pipeline: wgpu::RenderPipeline,
     uniform_buffer: wgpu::Buffer,
     bind_group: wgpu::BindGroup,
+    scene_scale: f32,
 }
 
 impl RenderPipeline {
-    pub fn new(device: &wgpu::Device, format: wgpu::TextureFormat, wgsl_source: &str) -> Result<Self> {
+    pub fn new(device: &wgpu::Device, format: wgpu::TextureFormat, wgsl_source: &str, scene_scale: f32) -> Result<Self> {
         let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
             label: Some("scene"),
             source: wgpu::ShaderSource::Wgsl(wgsl_source.into()),
@@ -42,7 +49,9 @@ impl RenderPipeline {
                 ty: wgpu::BindingType::Buffer {
                     ty: wgpu::BufferBindingType::Uniform,
                     has_dynamic_offset: false,
-                    min_binding_size: None,
+                    min_binding_size: wgpu::BufferSize::new(
+                        std::mem::size_of::<Uniforms>() as u64
+                    ),
                 },
                 count: None,
             }],
@@ -92,7 +101,7 @@ impl RenderPipeline {
             cache: None,
         });
 
-        Ok(Self { pipeline, uniform_buffer, bind_group })
+        Ok(Self { pipeline, uniform_buffer, bind_group, scene_scale })
     }
 
     pub fn update_uniforms(
@@ -105,12 +114,14 @@ impl RenderPipeline {
     ) {
         let uniforms = Uniforms {
             resolution: [width as f32, height as f32],
-            time,
-            _pad0: 0.0,
+            viewport_offset: [0.0, 0.0],
             camera_pos: camera.position(),
-            _pad1: 0.0,
+            time,
             camera_target: camera.target,
             fov: camera.fov,
+            render_flags: [1.0, 1.0, 1.0, 0.0],
+            scene_scale: self.scene_scale,
+            _pad: [0.0; 3],
         };
         queue.write_buffer(&self.uniform_buffer, 0, bytemuck::bytes_of(&uniforms));
     }
diff --git a/crates/cord-shader/src/codegen_trig.rs b/crates/cord-shader/src/codegen_trig.rs
index ce102b0..53c692c 100644
--- a/crates/cord-shader/src/codegen_trig.rs
+++ b/crates/cord-shader/src/codegen_trig.rs
@@ -87,7 +87,9 @@ r#"struct Uniforms {
     fov: f32,
     render_flags: vec4<f32>,
     scene_scale: f32,
-    _pad: vec3<f32>,
+    _pad1: f32,
+    _pad2: f32,
+    _pad3: f32,
 };
 
 @group(0) @binding(0) var<uniform> u: Uniforms;